Since Windows-XP was introduced there has been a free un-zipping program built into Windows. It is included with XP, Vista, and Win-7 operating systems. Just double click on a zipped file and Windows will open the file for you.

Choose "EXTRACT ALL" under the FILE menu. All the files inside the zip archive wil be placed into a non-zipped folder with the same name as the zip file and in the same directory as the zip file you just opened.